Method for fabricating organic electroluminescent device

ABSTRACT

A method for fabricating an organic electroluminescent device (OLED) includes the following steps. First, a substrate is provided. Next, an anode layer is formed on the substrate. Next, a buffer layer is formed on the anode layer, wherein the buffer layer include a CF x  film (fluorinated carbon films) containing carbon-fluoride bonded molecules. Next, a treatment process is performed on the CF x  film to convert the carbon-fluoride bonded molecules into carbon-carbon bonded molecules. A plurality of organic layers is formed on the buffer layer. A cathode layer is formed on the organic layer. Because the buffer layer has a better conductivity, the organic electroluminescent device (OLED) of the present invention has a better luminous efficiency.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 94142426, filed on Dec. 2, 2005. All disclosure of the Taiwanapplication is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for fabricating an organicelectroluminescent device (OLED), and more particularly to a method forfabricating a carbon-enriched film with high conductivity and a methodfor fabricating an organic electroluminescent device (OLED) employingthe carbon-enriched film as the buffer layer thereof.

2. Description of the Related Art

Display serving as an interface between human and information plays asignificant role in everyday activities. Currently flat panel displayshave become the major trend in the display field. Wherein in particular,an organic electroluminescent display has enormous potential and isexpected to become the main stream of the next generation flat paneldisplays, thanks to its predominant advantageous features, such asself-emitting, no viewing angle dependency, power-saving, simplerprocess, low-cost, lower operation temperature range, fast response andfull colorization.

An organic electroluminescent display mainly takes advantage of theself-emitting nature of an organic electroluminescent device (OLED) toachieve displaying effect. Wherein, the organic electroluminescentdisplay mainly comprises a pair of electrodes and an organic layer. Whencurrent flows between the anode and the cathode, electrons and holes inthe organic layer are recombined to produce excitons and enables theorganic layer to produce lights with different colors depending on thematerial property of the organic layer. Thus, a luminous display isachieved.

FIG. 1 is a schematic view of a structure of a conventional organicelectroluminescent device (OLED). Referring to FIG. 1, a conventionalOLED 100 includes a substrate 110, an anode layer 120, a holetransporting layer (HTL) 130, an organic electroluminescent layer (OEL)140, an electron transporting layer (ETL) 150 and a cathode layer 160.As an offset voltage is applied between the anode layer 120 and thecathode layer 160, electrons are injected into the electron transportinglayer (ETL) 150 from the cathode layer 160 and are transmitted to theorganic electroluminescent layer (OEL) 140, while holes are injectedinto the hole transporting layer (HTL) 130 from the anode layer 120.Further, the injected holes are transmitted to the organicelectroluminescent layer (OEL) 140, where the electrons and the holesare recombined to generate excitons and produce luminous effect.

The anode layer 120 is typically comprised of an indium tin oxide (ITO)material, and therefore the contact interface between the ITO (aninorganic material) and the hole transporting layer (HTL) 130 (anorganic material) has a poor electrical contact. In order to resolve theabove problem some proposed suppressing the switching current bytreating the surface of the ITO anode layer with an UV-ozone and aplasma. However, exposure of the surface of the anode layer 120 to theUV-ozone and plasma may damaged the surface of the anode layer 120,which may adversely affect electrical properties of the anode layer 120.

Some others propose disposing a buffer layer (not shown) between theanode layer 120 and the hole transporting layer (HTL) 130. However theconductivity of the buffer layer is poor, which lower the luminousefficiency of the organic electroluminescent device (OLED) 100.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a methodfor fabricating an organic electroluminescent device (OLED) suitable forfabricating an organic electroluminescent display device having betterluminous efficiency.

Another object of the present invention is to provide a method forfabricating a carbon-enriched film with high conductivity suitable forserving as a hole injection layer (HIL) and a hole transporting layer(HTL) in an OLED and thereby further improving the OLED luminousefficiency.

According to an embodiment of the present invention, first, a substrateis provided. Next, an anode layer is formed over the substrate. Next, abuffer layer is formed over the anode layer, wherein the buffer layer isformed by, for example, forming a CF_(x) film (fluorinated carbon film)containing carbon-fluoride bonded molecules on the anode layer andperforming a treatment process to treat the CF_(x) film (fluorinatedcarbon film) for converting the carbon-fluoride bonded molecules intocarbon-carbon bonded molecules. Furthermore, a plurality of organiclayers is formed on the buffer layer. Finally, a cathode layer is formedon the organic layer.

In an embodiment of the present invention, the treatment processincludes at least an ultraviolet irradiation process or a plasmatreatment process.

In an embodiment of the present invention, the ultraviolet irradiationprocess employs an ultraviolet light with a wavelength of about 180nm˜260 nm, preferably with a wavelength of about 185 nm or 254 nm.

In an embodiment of the present invention, the ultraviolet irradiationprocess employs an ultraviolet light with a light intensity of about 270mJ/cm²˜810 mJ/cm², preferably a light intensity of about 270 mJ/cm² or810 mJ/cm².

In an embodiment of the present invention, the plasma treatment processutilizes employs a gas containing argon (Ar) or nitrogen (N₂).

In an embodiment of the present invention, the carbon-fluoride bondedmolecule includes one of CF₁ (carbon unifluoride bonded molecule), CF₂(carbon bifluoride bonded molecule), CF₃ (carbon trifluoride bondedmolecule), C—CF_(n) (carbon-carbon n-fluoride bonded molecule) and acombination thereof.

In an embodiment of the present invention, the CF_(x) film may be formedby performing, for example, a plasma chemical vapor deposition (plasmaCVD) process.

In an embodiment of the present invention, the buffer layer can be usedto serve as a hole injection layer (HIL) and a hole transporting layer(HTL).

In an embodiment of the present invention, the organic layer may beformed by, for example, sequentially forming a hole transporting layer(HTL), an organic electroluminescent layer (OEL), an electrontransporting layer (ETL) and forming an electron injection layer (EIL)over the buffer layer.

In an embodiment of the present invention, the hole transporting layer(HTL) includes NPB (8-naphylhenyidiamine).

In an embodiment of the present invention, the a organicelectroluminescent layer (OEL) includes a blended luminescence materialdoped with AlQ₃ (aluminum tris (8-hydroxyquinoline)).

In an embodiment of the present invention, the electron transportinglayer (ETL) includes AlQ₃ (aluminum tris (8-hydroxyquinoline)).

In an embodiment of the present invention, the electron injection layer(EIL) includes LiF (lithium fluoride).

In an embodiment of the present invention, the anode layer includesmetal or transparent conductive material.

In an embodiment of the present invention, the cathode layer includesmetal or transparent conductive material.

The present invention further provides a method for fabricating acarbon-enriched film including the following steps. First, a substrateis provided. Next, a CF_(x) film (fluorinated carbon film) is formed onthe substrate, wherein the CF_(x) film contains carbon-fluoride bondedmolecules. Next, a treatment process is performed on the CF_(x) film soas to convert the carbon-fluoride bonded molecules into carbon-carbonbonded molecules.

In an embodiment of the present invention, the treatment processincludes an ultraviolet irradiation process or a plasma treatmentprocess.

In an embodiment of the present invention, the ultraviolet irradiationprocess employs an ultraviolet light with a wavelength of about 180nm˜260 nm, preferably about 185 nm or 254 nm.

In an embodiment of the present invention, the ultraviolet irradiationprocess employs an ultraviolet light with a light intensity of about 270mJ/cm²˜810 mJ/cm², preferably 270 mJ/cm² or 810 mJ/cm².

In an embodiment of the present invention, the plasma treatment processemploys a gas containing argon (Ar) or nitrogen (N₂).

In an embodiment of the present invention, the carbon-fluoride bondedmolecule includes one of CF₁ (carbon unifluoride bonded molecule), CF₂(carbon bifluoride bonded molecule), CF₃ (carbon trifluoride bondedmolecule), C—CF_(n) (carbon-carbon n-fluoride bonded molecule) and acombination thereof.

In an embodiment of the present invention, the CF_(x) film may be formedby performing, for example, plasma chemical vapor deposition (plasmaCVD) process.

The present invention employs a treatment process to convert thecarbon-fluoride bonded molecules in the CF_(x) film into carbon-carbonbonded molecules for producing a carbon-enriched film for improving theelectrical conductivity and the thermal stability. Furthermore, thecarbon-enriched film is disposed between the anode layer and the holetransporting layer (HTL) in the organic electroluminescent device (OLED)to improve the interface property between the anode layer and the HTLand thereby substantially improve luminous efficiency and brightness ofthe OLED device.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve for explaining theprinciples of the invention.

FIG. 1 is a schematic view of a structure of a conventional organicelectroluminescent device (OLED).

FIG. 2A˜FIG. 2F are schematic cross-sectional views showing a methodflowchart for fabricating an organic electroluminescent device (OLED)according to an embodiment of the present invention.

FIG. 3 is a relative luminous efficiency diagram of different organicelectroluminescent devices (OLEDs).

FIG. 4A˜FIG. 4C are schematic cross-sectional views showing a methodflowchart for fabricating a carbon-enriched film according to anembodiment of the present invention.

FIG. 5A is an X-ray photoelectron spectrogram of the CF_(x) film(fluorinated carbon film) prior to being treated.

FIG. 5B is an X-ray photoelectron spectrogram of the CF_(x) film(fluorinated carbon film) after being treated.

DESCRIPTION OF THE EMBODIMENTS

FIG. 2A˜FIG. 2F are schematic cross-sectional views showing a methodflowchart for fabricating an organic electroluminescent device (OLED)according to an embodiment of the present invention.

First, a substrate 210 is provided, as shown in FIG. 2A. In anembodiment, the substrate 210 may be a glass substrate, a plasticsubstrate or a flexible substrate.

Next, as shown in FIG. 2B, an anode layer 220 is formed on the substrate210. In an embodiment, the anode layer 220 may be formed by performing asputtering or evaporation process. The anode layer 220 comprises metalor transparent conductive material including, for example, indium tinoxide (ITO), tin oxide, gold, silver, platinum or copper.

Next, as shown in FIGS. 2C and 2D, a buffer layer 230′ is formed on theanode layer 220, wherein the the buffer layer 230′ is formed by, forexample, forming a CF_(x) film (fluorinated carbon film) 230 on theanode layer 220 containing a plurality of carbon-fluoride bondedmolecules (not shown in the figure); performing a treatment process 240on the CF_(x) film 230 to convert the carbon-fluoride bonded moleculesinto carbon-carbon bonded molecules (not shown) for forming acarbon-enriched film.

Referring to FIG. 2C, in an embodiment of the present invention, theCF_(x) film 230 may be formed by using, for example, a plasma chemicalvapor deposition (plasma CVD) process including, for example, placingthe substrate 210 in a vacuum chamber (not shown in the figure),charging a CHF₃ gas (trifluoromethane gas) into the vacuum chamber andapplying a voltage between a pair of electrodes (not shown in thefigure) for producing a plasma gas containing carbon atoms and fluorineatoms. Next, the plasma gas is diffused onto the anode layer 220, thecarbon atoms and the fluorine atoms are aggregated in variousproportions to form a CF_(x) film (fluorinated carbon film) 230 with aplurality of carbon-fluoride bonded molecules.

In particular, the deposition rate of the CF_(x) film 230 may be carriedout at a low deposition rate (LDR) or a high deposition rate (HDR).However, the deposition rate does not affect the film composition. In anembodiment, the above-described carbon-fluoride bonded molecules can beone of CF₁ (carbon unifluoride bonded molecule), CF₂ (carbon bifluoridebonded molecule), CF₃ (carbon trifluoride bonded molecule), C—CF_(n)(carbon-carbon n-fluoride bonded molecule) and a combination thereof.

Referring to FIG. 2D, in an embodiment, the treatment process 240includes an ultraviolet irradiation process or a plasma treatmentprocess.

According to an embodiment of the present invention, the ultravioletirradiation process employs an ultraviolet light with a wavelength ofabout 180 nm˜260 nm, preferably about 185 nm or 254 nm, and a lightintensity of about 270 mJ/cm²˜810 mJ/cm² and preferably of about 270mJ/cm² or 810 mJ/cm². Under the above condition, the energy of theultraviolet breaks the bonded of the carbon-fluoride bonded molecules inthe CF_(x) film 230 and re-bonds the carbon atoms to form carbon-carbonbonded molecules. The composition of the buffer layer 230′ as shown inFIG. 2D mostly comprises carbon-carbon bonded molecules.

Since the carbon atom herein possesses sp2 electronic orbital, theelectrons are more easy delivered, which renders the buffer layer 230′with an excellent conductivity and can be used as a hole injection layer(HIL) and a hole transporting layer (HTL).

In another embodiment, the treatment process 240 may include a plasmatreatment process employing a gas containing argon gas (Ar) or nitrogengas (N₂). In the plasma treatment process, ion bombardment of the argongas plasma or the nitrogen gas plasma breaks the bonded of thecarbon-fluoride bonded molecules in the CF_(x) film 230 and re-bond thecarbon atoms form carbon-carbon bonded molecules.

Further, a plurality of organic layers 250 are formed on the bufferlayer 230′, as shown in FIG. 2E. In an embodiment, the organic layers250 may be formed by sequentially forming a hole transporting layer(HTL) 252, an organic electroluminescent layer (OEL) 254, an electrontransporting layer (ETL) 256 and an electron injection layer (EIL) 258on the buffer layer 230′ by using well known methods including coating,evaporation or sputtering methods.

In an embodiment, the hole transporting layer (HTL) 252 includes NPB(α-naphylhenyidiamine), the organic electroluminescent layer (OEL) 254includes blended luminescence material doped with AlQ₃ (aluminum tris(8-hydroxyquinoline)), the electron transporting layer (ETL) 256includes AlQ₃ (aluminum tris (8-hydroxyquinoline)) and the electroninjection layer (EIL) 258 includes LiF (lithium fluoride). However, itshould be noted that the present invention is not limit the abovematerials. Other suitable materials may also be used to achieve thepurpose of the present invention, and is construed to be within thescope of the present invention.

Furthermore, a cathode layer 260 is formed on the organic layer 250, asshown in FIG. 2F. In an embodiment, the cathode layer 260 may be formedby performing a sputtering or an evaporation process. The cathode layer260 may include a metal or a transparent conductive material,comprising, for example, aluminum, silver or indium tin oxide (ITO).

Thus, an organic electroluminescent device (OLED) 200 of the presentinvention is obtained, as shown in FIG. 2F. In an embodiment, theorganic electroluminescent device (OLED) 200 comprises a stackedstructure including the buffer layer 230′, the hole transporting layer(HTL) 252, the organic electroluminescent layer (OEL) 254, the electrontransporting layer (ETL) 256, the electron injection layer (EIL) 258 andthe cathode layer 260, and may be exemplified byC—C_(n)/NPB/C545T+AlQ₃/AlQ₃/LiF/Al, and the thicknesses of the layersare 3 nm/60 nm/35 nm/15 nm/1 nm/1000 nm, respectively.

To prove that the organic electroluminescent device (OLED) 200 includingthe buffer layer 230′ of the present invention has a better luminousefficiency, OLEDs including a CF_(x) film 230 not treated by thetreatment process 240 and OLEDs including carbon-enriched films weretested for the relative luminous efficiency under an identical testingconditions, for example using the same applied voltage, and the testresults are shown in FIG. 3.

FIG. 3 is a relative luminous efficiency measurement of differentorganic electroluminescent devices (OLEDs). Referring to FIG. 3, a curve310 represents the relative luminous efficiency of OLEDs comprising aCF_(x) film formed with a high deposition rate (HDR), while a curve 320represents the relative luminous efficiency of OLEDs comprising a CF_(x)film with a low deposition rate (LDR). FIG. 3 also shows relativeluminous efficiency measurement of different organic electroluminescentdevices (OLEDs) including the buffer layer without being treated withthe treatment process and the buffer layer being treated with thetreatment process are shown.

As can be seen from the curves 310 and 320 that the OLED comprising aCF_(x) film without being treated with the treatment process has arelative luminous efficiency of about 4000 cd/m², whereas the OLEDcomprising a CF_(x) film being treated with the treatment process has agreater luminous efficiency as shown in FIG. 3. In particular, as shownby the curve 310 and the curve 320, it is clear that the OLED comprisinga CFx film treated with the treatment process 240 including anultraviolet irradiation process employing an ultraviolet light with awavelength of 810 mJ/cm² has the best luminous efficiency, wherein theOLED luminous efficiency is increased by 50% or so.

In summary, by disposing a buffer layer 230′ treated with the treatmentprocess 240 between the anode layer 220 and the organic layer 250 of theOLED 200 shown in FIG. 2F, the contact between the anode layer 220 andthe organic functional group layer 250 can be improved. According to thepresent invention, the buffer layer 230′ is treated with the treatmentprocess 240 to modify the composition of the buffer layer 230′ mainlywith carbon-carbon bonded molecules, wherein the carbon atom possessessp2 electronic orbital, which will deliver the electrons more easily andthereby readily promote conductivity of the buffer layer 230′. Thus, theluminous efficiency of the OLED 200 can be effectively promoted.

FIG. 4A˜FIG. 4C are schematic cross-sectional views showing a flowchartfor fabricating a carbon-enriched film according to an embodiment of thepresent invention.

Referring to FIG. 4A, first, a substrate 400 is provided. In anembodiment, the substrate 400 can be a glass substrate, a plasticsubstrate or a flexible substrate.

Next, referring to FIG. 4B, a CF_(x) film (fluorinated carbon film) 410is formed on the substrate 400. The CF_(x) film 410 is comprised of apolymeric material having a plurality of carbon-fluoride bondedmolecules (not shown in the figure). The CF_(x) film 410 may be formedby, for example, performing a plasma chemical vapor deposition (plasmaCVD) process. Particularly in an embodiment, the above-describedcarbon-fluoride bonded molecules can be one of CF₁ (carbon monofluoridebonded molecule), CF₂ (carbon difluoride bonded molecule), CF₃ (carbontrifluoride bonded molecule), C—CF_(n) (carbon-carbon n-fluoride bondedmolecule) and a combination thereof.

Thereafter, referring to FIG. 4C, a treatment process 420 is performedon the CF_(x) film 410, so as to convert the carbon-fluoride bondedmolecules into carbon-carbon bonded molecules (not shown) for forming acarbon-enriched film 410′. In an embodiment, the treatment process 420includes an ultraviolet irradiation process or a plasma treatmentprocess.

Acorrding to an embodiment of the present invention, the ultravioletirradiation process employs an ultraviolet light having a wavelength ofabout 180 nm˜260 nm, preferably an ultraviolet light having a wavelengthof about 185 nm or 254 nm. Furthermore, the light intensity of the UVlight is about 270 mJ/cm²˜810 mJ/cm² and preferably, a light intensityof about 270 mJ/cm2 or 810 mJ/cm². Thus, the CF_(x) film 410 havingcarbon-fluoride bonded molecules may be converted into a carbon-enrichedfilm 410′ containing carbon-carbon bonded molecules.

Referring to FIG. 4C again, in another embodiment, the treatment process420 can be the plasma treatment process as well, which employs a gascontaining argon (Ar) or nitrogen (N₂). The plasma treatment process maybe employed for converting carbon-fluoride bonded molecules in theCF_(x) film 410 into a carbon-enriched film 410′ containingcarbon-carbon bonded molecules.

According to an embodiment of the present invention, the ultravioletirradiation process provides a better effect in converting thecarbon-fluoride bonded molecules in the CF_(x) film 410 into acarbon-enriched film 410′ containing carbon-carbon bonded molecules. AnX-ray photoelectron spectrometer (XPS) may be used to measure themolecule composition of the CF_(x) film 410 before subjecting the CF_(x)film 410 to the treatment process 420 and the molecule composition ofthe carbon-enriched film 410′ obtained after treating the CF_(x) film410 with the treatment process 420, and the results are shown in FIGS.5A and 5B.

FIG. 5A is an X-ray photoelectron spectrogram of the CF_(x) film(fluorinated carbon film) before being subjected to the treatmentprocess 420. FIG. 5B is an X-ray photoelectron spectrogram of the CF_(x)film (fluorinated carbon film) after being subjected to the treatmentprocess. Referring to FIG. 5A, the noticeable signals of CF₁, CF₂, CF₃and C—CF_(n) appearing on the X-ray photoelectron spectrogram (XPSspectrogram) indicate that the composition of the CF_(x) film 410 beforebeing treated mainly contains CF₁, CF₂, CF₃ and C—CF_(n). bondedmolecules. Referring to FIG. 5B, it can be seen that after being treatedby the treatment process 420, in particular after the ultravioletirradiation process, all signals of carbon-fluoride bonded molecules arealmost disappeared on the XPS spectrogram. Instead, the signal of thecarbon-carbon bonded molecules is apparent, indicating thecarbon-enriched film 410′ obtained after the treatment containscarbon-carbon bonded molecules mainly.

Since the carbon atom herein possesses sp2 electronic orbital, thecarbon-enriched film 410′ has an excellent electrical conductivity. Thecarbon-enriched film 410′ may also be used to serve as a hole injectionlayer (HIL) and a hole transporting layer (HTL) in the OLED. Thus, theOLED luminous efficiency can be effectively promoted. In addition, theabove-described method for fabricating the carbon-enriched film issimple and the carbon-enriched film 410′ also has a better thermalstability.

In summary, the method for fabricating the OLED and the method forfabricating the carbon-enriched film of the present invention has atleast the following advantages:

-   -   (1) The OLED of the present invention employs a carbon-enriched        film with high conductivity as a buffer layer, which is capable        of promoting the OLED luminous efficiency.    -   (2) The method for fabricating the carbon-enriched film is        simple, wherein an ultraviolet irradiation process may be        employed to convert the CF_(x) film into the carbon-enriched        film containing carbon-carbon bonded molecules.    -   (3) The carbon-enriched film mainly contains carbon-carbon        bonded molecules, and therefore, the carbon-enriched film has a        better conductivity and a better thermal stability.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the specification andexamples to be considered as exemplary only, with a true scope andspirit of the invention being indicated by the following claims andtheir equivalents.

1. A method for fabricating an organic electroluminescent device (OLED),comprising: providing a substrate; forming an anode layer on thesubstrate; forming a buffer layer on the anode layer, wherein the bufferlayer comprises a fluorinated carbon film containing carbon-fluoridebonded molecules; performing a treatment process on the fluorinatedcarbon film to convert the carbon-fluoride bonded molecules intocarbon-carbon bonded molecules to form a carbon-enriched film, whereincarbon atoms in the carbon-enriched film possess sp² electronic orbital;forming a plurality of organic layers on the carbon-enriched film; andforming a cathode layer on the organic layers.
 2. The method forfabricating an OLED as recited in claim 1, wherein the treatment processcomprises an ultraviolet irradiation process or a plasma treatmentprocess.
 3. The method for fabricating an OLED as recited in claim 2,wherein the ultraviolet irradiation process employs an ultraviolet lightwith a wavelength of about 180 nm˜260 nm.
 4. The method for fabricatingan OLED as recited in claim 3, wherein the wavelength of the ultravioletlight is about 185 nm or 254 nm.
 5. The method for fabricating an OLEDas recited in claim 2, wherein the ultraviolet irradiation processemploys an ultraviolet light with an intensity of about 270 mJ/cm2˜810mJ/cm2.
 6. The method for fabricating an OLED as recited in claim 5,wherein the light intensity of the ultraviolet light is about 270 mJ/cm²or 810 mJ/cm².
 7. The method for fabricating an OLED as recited in claim2, wherein the gas the plasma treatment process employs a gas containingargon (Ar) or nitrogen (N₂).
 8. The method for fabricating an OLED asrecited in claim 1, wherein the carbon-fluoride bonded moleculesincludes one of CF₁ (carbon monofluoride bonded molecule), CF₂ (carbonbifluoride bonded molecule), CF₃ (carbon trifluoride bonded molecule),C—CF_(n) (carbon-carbon n-fluoride bonded molecule) and a combinationthereof.
 9. The method for fabricating an OLED as recited in claim 1,wherein the fluorinated carbon film is formed by performing a plasmachemical vapor deposition process.
 10. The method for fabricating anOLED as recited in claim 1, wherein the buffer layer comprises a holeinjection layer (HIL) and a hole transporting layer (HTL).
 11. Themethod for fabricating an OLED as recited in claim 1, wherein the methodfor forming the organic layer on the buffer layer comprises sequentiallyforming a hole transporting layer (HTL), an organic electroluminescentlayer (OEL), an electron transporting layer (ETL) and an electroninjection layer (EIL) over the buffer layer.
 12. The method forfabricating an OLED as recited in claim 11, wherein the holetransporting layer (HTL) comprises NPB (.-naphylhenyldiamine).
 13. Themethod for fabricating an OLED as recited in claim 11, wherein theorganic electroluminescent layer (OEL) comprises a blended luminescencematerial doped with AlQ3 (aluminum tris (8-hydroxyquinoline)).
 14. Themethod for fabricating an OLED as recited in claim 11, wherein theelectron transporting layer (ETL) comprises AlQ₃ (aluminum tris(8-hydroxyquinoline)).
 15. The method for fabricating an OLED as recitedin claim 11, wherein the electron injection layer (EIL) comprises LiF(lithium fluoride).
 16. The method for fabricating an OLED as recited inclaim 1, wherein the anode layer comprises metal or transparentconductive material.
 17. The method for fabricating an OLED as recitedin claim 1, wherein the cathode layer comprises metal or transparentconductive material.